Implantable trilayer microneedle transdermal delivery system to enhance bioavailability and brain delivery of rivastigmine for Alzheimer treatment: A proof-of-concept study.

Alzheimer's disease (ALZ) is a neurological disorder characterized by cognitive decline. Rivastigmine (RV), an acetylcholinesterase inhibitor, is commonly used to treat ALZ. Unfortunately, RV is availablein capsule form, which is associated with low drug bioavailability, and in patch form, which can lead to skin irritation upon repeated use. This study successfully fabricated a trilayer dissolving microneedle (TDMN) containing RV with adequate mechanical strength by using the molding method. In vitro release and ex vivo permeation showed that the release and permeation of RV were significantly sustained compared to control without PCL. The release and permeation percentages were 91.34 ±â€¯11.39 % and 13.76 ±â€¯1.49 µg/cm2, respectively. In addition, the concentration of RV in plasma and brain after 168 h was measured to be 0.44 ±â€¯0.09 µg/mL and 1.23 ±â€¯0.26 µg/g, respectively, which reached the minimum concentration to inhibit AcHE and BuChe. Pharmacokinetic testing revealed higher AUC values after administration of TDMN, indicating better bioavailability, and RV concentrations in the brain were found to be twice as high as those achieved with oral administration. This study suggests TDMN may enhance the bioavailability and brain delivery of RV.